(Not Applicable)
(Not Applicable)
1. Field of the Invention
This invention relates generally to food-processing machines, and more specifically to an apparatus for coating substrates with fluent materials.
2. Description of the Related Art
In the food processing field, it is desirable to apply consistent quantities of food products, such as meat, cheese and sauces to a substrate rapidly to provide a consistent product to consumers at a high rate of speed. That way, when a product is marked as containing a particular quantity of food, it contains that quantity, not less.
Consistency in food quantity also makes the cost of making each food product more predictable. If measurement of the quantity of food product is inaccurate, the amount of food in a food product marked as containing a particular quantity has to be exceeded to ensure that at least the marked quantity is present. The amount of excess varies due to inaccuracies, and therefore the costs vary.
Consistency in food product presentation is also important. For example, the upper surface of a pizza crust must be coated with pizza sauce prior to the addition of toppings, such as cheese, meat and vegetables. Pizza sauce is a fluent slurry of tomato sauce and other ingredients. Some pizza makers prefer the crust to be coated to within a fraction of an inch from the edge of the crust, while others prefer the crust to be coated essentially to the edge. Regardless of the amount of the crust that is coated, the crust must be coated evenly for a consistent presentation, and this takes time.
The conventional methods of coating pizza crusts include manual and automated methods. The manual methods include pouring a measured amount of sauce onto the crust and spreading. The conventional methods of spreading the sauce include tilting the crust in various directions to cause the sauce to spread by flowing due to gravity. This method takes a lot of experience to get the sauce to flow only where desired. Furthermore, different sauces have different material characteristics, such as viscosity and slurry particle size, which affect flow characteristics.
The second manual method of spreading includes the use of an instrument, such as a spoon or spatula, to push the sauce to the places on the crust that it is desired. However, both the tilting and the pushing methods of spreading sauce result in uneven application of sauce, which results in inconsistent presentation.
It is known to automate the application of fluent materials to substrates. U.S. Pat. Nos. 2,872,245 to Groth, 3,631,818 to Zito, 3,648,596 to Zito, 3,982,033 to Zito, 4,197,794 to Raque et al., 5,318,629 to Raque et al., 5,855,670 to Usgaard et al., 5,988,521 to Nohynek and Re. 36,178 to Freudinger et al. show devices for automating the food product application process.
The ""033 and ""818 patents to Zito show a pizza crust conveyed along a conveyor beneath a nozzle. Once the crust is detected by a sensor, a central controller signals the conveyor to stop, the nozzle pours sauce onto the crust while rotating. The nozzle has a downwardly extending arm with a head at the bottom into which the sauce flowing down through the arm goes before being spread outwardly by the arm. Some of the other patents cited show mechanisms for dispensing liquids or other food particulate material onto substrates below, and many refer to waterfall cascading of liquid or particulate onto an awaiting surface.
One of the problems with the conventional automated means for applying fluent materials is inaccuracy in placing the fluent material at the place desired on the substrate. For example, the cascading of fluent material normally results in the material being applied in undesirable places, such as the edges of the crust. An additional problem is that product is wasted when the fluent material is cascaded onto areas that are not food substrates, which includes a part of a conveyor at the edges of round pizza crusts where gaps are formed between the crusts.
Additional problems result from automated machines that are too slow or are unable to adapt to fluent materials of characteristics that vary from those the machines were designed to apply. Furthermore, many of the machines are designed for use in a continuous process, whereas some situations call for a batch process.
An example of such a situation is a pizza restaurant. Continuous process automated machines are not conducive to pizza making at pizza restaurants, because in this environment each pizza must be custom-made for each consumer. There are normally various crust thicknesses and sizes, and pizza restaurants must be able to make pizzas of every possible iteration within a short time period. Automated machines do not work well in this environment, and manual methods of applying sauce are not fast enough.
Therefore, the need arises for an apparatus that applies sauce evenly and accurately to exactly the portion of any of the sizes of crusts desired.
The invention is an apparatus for coating an upper surface of a substrate with fluent material, such as pizza sauce on a pizza crust. The apparatus comprises a housing to which the elements of the invention are mounted. A first linear prime mover is connected to the housing and has a drive shaft displaceable along a longitudinal axis. A cylinder block is connected to the housing and has a cavity bounded by a cylindrical sidewall. A piston is drivingly linked to the drive shaft and is slidably mounted within the cavity. The piston has an end surface and an outer cylindrical surface, and the outer cylindrical surface seats against the cylindrical sidewall of the cylinder block forming a seal, thereby forming a chamber defined by the cylindrical sidewall and the piston end surface.
A supply conduit is connected to the cylinder block, and has a fluid passageway in fluid communication with a reservoir of fluent material. An inlet is formed in the cylinder block at the supply conduit for permitting fluid flow between the chamber and the passageway of the supply conduit. A nozzle is connected to the cylinder block and has a fluid passageway through it. An outlet is formed in the cylinder block near the nozzle for permitting fluid flow between the chamber and the nozzle""s fluid passageway. A turntable is rotatably mounted to the housing beneath the nozzle. The turntable is drivingly linked to a rotary motor for rotating the substrate beneath the nozzle to receive fluent material on the upper surface of said substrate.
In a preferred embodiment, there is a drive member rigidly mounted to the drive shaft, and there is a plurality of pistons, at least some of which are drivingly linked to the drive member. Each of the pistons has an end surface and an outer cylindrical surface. A plurality of cylinder block cavities are also contemplated, each of which is bounded by a cylindrical sidewall, and each of the pistons is slidably mounted in a corresponding one of the cavities with each outer cylindrical piston surface sealingly seating against the corresponding cavity""s cylindrical sidewall. This combination thereby forms a plurality of sealed chambers, each chamber being defined by one of the cylindrical sidewalls and one of the piston""s end surfaces.
There are also, in this preferred embodiment, a plurality of cylinder block connected nozzles, each nozzle having a fluid passageway through the nozzle, and each nozzle corresponding to one of the cavities. A plurality of cylinder block outlets are formed, wherein one outlet is between each one of the cavities and that cavity""s corresponding nozzle for permitting fluid flow between each of the chambers and each of the nozzles""fluid passageways.
In a still more preferred embodiment, a structure is provided for selectively linking the pistons to the drive member. Preferably, a solenoid is connected to the drive member, and the solenoid has a linearly displaceable solenoid drive shaft. A locking tab is connected to the solenoid drive shaft and is slidably mounted to the drive member near at least one of the pistons. The locking tab is releasably inserted by linear displacement of the solenoid drive shaft into a recess formed in one of the pistons. The solenoid and locking tab structure thereby drivingly link the piston to the drive member.